Repetition lever of grand piano

ABSTRACT

There is provided a repetition lever for a grand piano, which is excellent in shape retainability and dimensional stability and is light in weight and high in rigidity, thereby enabling required operations to be stably performed and improving the capability of repeated key striking. A repetition lever  4  for a grand piano, which performs the operation of pushing up a hammer  30  after the hammer has struck a string, is formed by a molded article of a thermoplastic resin containing long fibers for reinforcement, the molded article being molded by a long fiber process. The repetition lever  4  has reduced cross-sectional area portions  49, 50 , and  54  for reducing weight thereof. The long fibers for reinforcement are carbon fibers, and the thermoplastic resin is an ABS resin.

FIELD OF THE INVENTION

The present invention relates to a repetition lever for a grand piano,which performs the operation of pushing up a hammer after the hammer hasstruck a string, so as to ensure the capability of repeated key strikingin an acoustic grand piano or the like.

BACKGROUND ART

An action for a grand piano, including a repetition lever, is generallyconfigured as follows: The action of a grand piano is provided in amanner pivotally movable about a rear end thereof, and includes a wippendisposed on a rear part of a key, and a repetition lever and a jackwhich are pivotally mounted to the wippen. The repetition lever ismounted to the wippen in a state engaged with a bifurcatedlever-mounting part of the wippen. The repetition lever extends in thefront-rear direction, and a hammer is disposed on an upper surface ofthe repetition lever via a shank roller. The upper end of the jack isengaged in a jack guide hole formed in the repetition lever, and isopposed to the shank roller from below with a slight space therebetweenin a key-released state. Further, the repetition lever and the jack areurged in a returning direction by a repetition spring, and in thekey-released state, the jack is opposed to a regulating button frombelow with a slight space therebetween.

With the arrangement described above, when the key is depressed, thewippen is pushed up, whereby the repetition lever and the jack arepivotally moved upward along with the wippen. With this pivotal motion,the jack pushes up the hammer via the shank roller. Thereafter, when thehammer pivotally moves immediately close to a position for striking astring stretched above, the jack comes into engagement with theregulating button to be released from the shank roller. This disconnectsthe hammer from the action and the key and causes the hammer to strikethe string in a free rotation state. After having struck the string, thehammer pivotally moves in the opposite direction.

Then, when the key is released, the repetition lever is pivotallyreturned by the resilient force of the repetition spring to thereby pushup the hammer via the shank roller in timing in which the key isreturned to a predetermined height. As a consequence, the jack ispivotally returned by the resilient force of the repetition spring to bepositioned under the shank roller, whereby a following string-strikingoperation can be reliably performed even when the key is not completelyreturned. This ensure the capability of repeated key striking.

As is apparent from the above, the repetition lever is a component partfor pushing up the hammer via the shank roller after the hammer hasstruck the string, so as to attain repeated key striking, such as atrill in which the same key is repeatedly struck. Conventionally, ingeneral, the repetition lever is made of wood, similarly to many otheraction component parts. This is because wood is advantageous in that itis easily available and excellent in machinability as well as highlyrigid in spite of its light weight. In particular, the repetition leveris required to be not only light in weight for making pivotal motionlightly with quick response to key release so as to push up the hammerin predetermined timing responsive to the key release, but also highlyrigid so as to prevent the repetition lever from being largely warpedduring the operation of pushing up the hammer.

Further, a conventional repetition lever made of a synthetic resin hasbeen disclosed e.g. in Patent Literature 1. This repetition lever ismade of an ABS resin etc., and has a conductive coating or metal layerformed at least on a surface thereof so as to prevent the repetitionlever from being electrostatically charged.

As described above, wood is generally used as a material for theconventional repetition lever because wood is not only light but alsohigh in rigidity. However, since wood, which is a natural material,lacks homogeneity, it suffers from variations in rigidity and weight,and is prone to deformation, such as warpage or distortion, due toresidual stress. Further, wood undergoes large dimensional change due todryness and wetness, and hence relatively large transverse expansion orcontraction of the repetition lever occurs depending on humidity. As aresult, the clearance between the lever-mounting part of the wippen andthe repetition lever changes, which loosens or tightens engagementbetween the repetition lever and the wippen. The deformation of therepetition lever and the change in clearance between the lever-mountingpart of the wippen and the repetition lever can make the operation ofthe repetition lever unstable.

On the other hand, in the case where the repetition lever is made of theABS resin as disclosed in Patent Literature 1, since the ABS resin isexcellent in shape retainability and dimensional stability, the abovedescribed problems with the wooden repetition lever cannot occur.Further, the repetition lever made of the ABS resin is advantageous inthat it can be machined with high accuracy and material costs can bereduced. However, since the ABS resin has a larger specific gravity thanwood, the lightness of the repetition lever is impaired, which makes itsmotion slow. Further, since the ABS resin has a lower rigidity thanwood, the repetition lever made of the ABS resin is largely warped inpushing up the hammer, which causes a lag in timing in which the hammeris pushed up. Thus, the advantages of the wooden repetition lever arelost, and hence the capability of repeated key striking is degraded.

The present invention has been made in order to solve the aboveproblems, and an object thereof is to provide a repetition lever for agrand piano, which is excellent in shape retainability and dimensionalstability and is light in weight and high in rigidity, thereby enablingrequired operations to be stably performed and improving the capabilityof repeated key striking.

[Patent Literature 1] Japanese Laid-Open Patent Publication (Kokai) No.2003-5740

DISCLOSURE OF THE INVENTION

To attain the above object, the invention as claimed in claim 1 is arepetition lever for a grand piano, which performs the operation ofpushing up a hammer after the hammer has struck a string, wherein therepetition lever is formed by a molded article of a thermoplastic resincontaining long fibers for reinforcement, the molded article beingmolded by a long fiber process.

The above-mentioned long fiber process is for obtaining a molded articleby injection molding of a pellet that contains fibrous reinforcementshaving the same length and coated with a thermoplastic resin. Accordingto this long fiber process, differently from the case where a moldedarticle is molded by injection molding of a pellet simply containingshort fibers as reinforcements, relatively long fibrous reinforcementsare caused to be contained in the molded article. Therefore, therepetition lever according to the present invention contains relativelylong reinforcing long fibers, and hence can have a very high rigiditycompared with a repetition lever made only of a synthetic resin, such asan ABS resin. This makes it possible to obtain a rigidity not lower thanthat of a wooden repetition lever. As a consequence, it is possible tosuppress deflection of the repetition lever occurring in pushing up thehammer having struck the string, and thereby enabling the repetitionlever to perform the operation of pushing up the hammer in predeterminedtiming. Further, since the molded article molded by the long fiberprocess is as excellent in shape retainability and dimensional stabilityas the molded article of a single synthetic resin, it is possible toreduce deformation, such as warpage and torsion, of the repetition leverand expansion and contraction of the same due to dryness and wetness tomuch smaller amounts than in the case where the repetition lever is madeof wood. This makes it possible to ensure the stable operation of therepetition lever and enhance the capability of repeated key striking.

The invention as claimed in claim 2 is a repetition lever as claimed inclaim 1 wherein the long fibers have a length not shorter than 0.5 mm.

With this configuration, since the reinforcing long fibers having alength not shorter than 0.5 mm are contained in the molded article, itis possible to obtain a very high rigidity, and hence ensure a rigidityrequired for the repetition lever.

The invention as claimed in claim 3 is a repetition lever as claimed inclaim 1 or 2 wherein the long fibers are carbon fibers.

In general, carbon fibers have a higher electric conductivity than otherreinforcing long fibers, such as glass fibers. Therefore, by usingcarbon fibers as the reinforcing long fibers, the electric conductivityof the repetition lever is increased, whereby it is possible to reliablyrelease static electricity generated by friction between the repetitionlever and other component parts including the hammer, and therebyprevent the repetition lever from being electrostatically charged. Thismakes it possible to suppress attachment of dust to the repetition leverand its neighborhood, thereby maintaining excellent operation andappearance of the repetition lever.

The invention as claimed in claim 4 is a repetition lever as claimed inany one of claims 1 to 3 wherein the thermoplastic resin is an ABSresin.

In general, other component parts, such as a lever skin for contact witha drop screw, are attached to the repetition lever. The ABS resin has arelatively high adhesiveness among the thermoplastic resins, andtherefore by using the ABS resin as the thermoplastic resin for formingthe repetition lever, the lever skin and other component parts can beeasily mounted to the repetition lever by bonding, which increases theease of assembly of the repetition lever.

The invention as claimed in claim 5 is a repetition lever as claimed inany one of claims 1 to 4 wherein the repetition lever has a reducedcross-sectional area portion for reducing weight thereof.

With this configuration, since the reduced cross-sectional area portioncontributes to reduction of the weight of the repetition lever, it ispossible to enhance the lightness of the repetition lever. Further,according to the present invention, since the repetition lever has itsrigidity increased by the reinforcing long fibers as described above, arigidity required for the repetition lever can be maintained in spite ofthe reduction of the cross section of the repetition lever by thereduced cross-sectional area portion. Thus, it is possible to reduce theweight of the repetition lever as much as possible while maintaining therequired rigidity, thereby improving the capability of repeated keystriking. Further, since the repetition lever is molded by injectionmolding, it is possible to form the reduced cross-sectional area portionwith ease and high accuracy during molding of the repetition lever.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1]

Views of a repetition lever for a grand piano, according to anembodiment of the present invention, in which (a) is a plan view, (b) isa side view, and (c) is a bottom view.

[FIG. 2]

A side view of a keyboard apparatus for a grand piano, including therepetition lever shown in FIG. 1.

[FIG. 3]

A diagram showing a result of a rigidity test carried out on therepetition lever, together with Comparative Example.

[FIG. 4]

A fragmentary enlarged side view of a portion A in (b) of FIG. 1.

[FIG. 5]

A cross-sectional view taken on line V-V of (a) of FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention will now be described in detail with reference to thedrawings showing a preferred embodiment thereof. In the followingdescription, a player's side of a grand piano (right side as viewed inFIG. 2) will be referred to as “front”, and a remote side from theplayer's side as “rear”. Further, a direction in which keys 2 arearranged is referred to as “the transverse direction”.

First, a repetition lever 4 will be described with reference to FIG. 1.In the present embodiment, the repetition lever 4 is formed by athermoplastic resin molded component which is molded by a long fiberprocess. For example, the repetition lever 4 is obtained by injectionmolding using a pellet as described below. The pellet is formed bycoating roving formed of carbon fibers oriented by application of apredetermined tensile force thereto, e.g. with an ABS resin, which is athermoplastic resin containing a rubbery polymer, extruded from anextruder. This makes it possible to cause the carbon fibers to becontained in the formed pellet without breaking the roving of carbonfibers when the pellet is formed, and hence carbon fibers having thesame length as that of the pellet can be contained in the pellet. In thepresent embodiment, the length of the pellet is set to 5 to 15 mm, sothat carbon fibers having a length of 0.5 to 2 mm are contained in therepetition lever 4 formed by injection molding using the pellet.

As shown in FIG. 1, the repetition lever 4 is a rod-like memberextending in the front-rear direction, and is formed integrally with awippen-mounting part 41 formed in a central part thereof, a shankroller-pushing part 42 extending forward from the wippen-mounting part41, and a lever button-mounting part 43 extending rearward from thewippen-mounting part 41.

The wippen-mounting part 41 has a rectangular cross section havingsubstantially fixed width and height, and a mounting hole 44 formounting the repetition lever 4 to a wippen 3 (see FIG. 2) is formed toextend through a central part of the wippen-mounting part 41 in thetransverse direction.

The shank roller-pushing part 42 is larger in width than thewippen-mounting part 41. The width of the shank roller-pushing part 42is gently increased toward the front, and the width of the front half ofthe shank roller-pushing part 42 is fixed. Further, the height of therear half of the shank roller-pushing part 42 is equal to that of thewippen-mounting part 41, and the upper surface of the front half of thesame slopes in a downwardly curved manner. The front half of the shankroller-pushing part 42 is formed with a jack guide hole 45 verticallyextending therethrough and elongated in the front-rear direction, andthe front end part of the upper surface of the front half is formed as askin-mounting part 46 for mounting a lever skin 39 (see FIG. 2) thereon.

As shown in FIG. 4, the lower surface of the front half of the shankroller-pushing part 42 is one step higher than that of the rear half ofthe same, whereby lower stepped parts 56 are formed between the fronthalf and the rear half. Further, grooves 57 are formed at respectivelocations close to the front side of the lower stepped parts 56. Thegrooves 57 extend vertically along the whole height in the respectiveleft and right outer side surfaces of the shank roller-pushing part 42.Front and rear edges of each groove 57 form marking lines 57 a and 57 a.The grooves 57 and the marking lines 57 a are at approximately rightangles to the lower surface of the shank roller-pushing part 42, and thefront surface of each lower stepped part 56 slopes at a predeterminedsmall angle relative to the associated marking line 57 a. The lowerstepped parts 56 and the marking lines 57 a are used as a reference inadjusting the angular position of the jack 5 of the action 1 withrespect to the repetition lever 4.

Further, the upper surface of the shank roller-pushing part 42 ischamfered. More specifically, each of left and right wall parts 45 a and45 a defining the jack guide hole 45 has its left and right upper edgeschamfered during molding to form rounded parts 45 b having a radius of0.2 to 0.5 mm.

The rear half of the shank roller-pushing part 42 has first recessedparts 49 (only one of which is shown) formed in respective left andright side surfaces thereof to form a reduced cross-sectional areaportion, with peripheries 48 thereof left unrecessed. More specifically,the first recessed part 49 is comprised of a portion 49 a having itsdepth progressively increased rearward from a location close to the jackguide hole 45, a portion 49 b having its depth progressively increasedupward part way from the lower periphery 48, and the other portion 49 chaving a fixed depth. The skin-mounting part 46 has a triangularprojection 47 projecting downward from a lower surface thereof, and hassecond recessed parts 50 (reduced cross-sectional area portions) formedin respective left and right half portions of the lower surface of thetriangular projection 47 with a transversely central portion of the sameleft unrecessed. Further, the lower surface of the shank roller-pushingpart 42 is formed with a groove 52 in which one end of a repetitionspring 6 (see FIG. 2) is engaged.

On the other hand, the lever button-mounting part 43 has approximatelythe same width as that of the rear end of the shank roller-pushing part42 and approximately the same height as that of the wippen-mounting part41. Further, the lever button-mounting part 43 has a lower surface whoserear end part is formed as a sloping surface sloping upward as itextends rearward, and a screw hole 51 for mounting a lever button 28(see FIG. 2) is formed in a manner obliquely extending through the leverbutton-mounting part 43 between the sloping surface and the uppersurface. The lever button-mounting part 43 have third recessed parts 54(only one of which is shown) formed in respective left and right sidesurfaces thereof to form a reduced cross-sectional area portion, withperipheries 53 thereof left unrecessed. Each of the third recessed parts54 has a predetermined fixed depth except a shallowly recessed portionaround the screw hole 51.

Next, the arrangement of the action 1 including the repetition lever 4constructed as above will be described with reference to FIG. 2. Theaction 1 is provided for each of the large number of keys 2 (only one ofwhich is shown). As shown in FIG. 2, the action 1 is comprised of thewippen 3 which is pivotally movable and extends in the front-reardirection, and the repetition lever 4 and the jack 5 which are pivotallymounted to the wippen 3. The action 1 is mounted between left and rightbrackets 21 and 21 (only one of which is shown). The left and rightbrackets 21 and 21 are rigidly secured to the respective left and rightend parts of a keyframe (not shown) on which the associated keys 2 areplaced, and a wippen rail 22 is disposed between the brackets 21 and 21.The rear end of the wippen 3 is pivotally mounted to wippen flanges 24screwed to the wippen rail 22. Each of the wippens 3 is disposed on acapstan button 25 provided on the rear part of the upper surface of theassociated key 2, via a wippen heel 26.

A hammer shank rail 23 extends between the left and right brackets 21and 21. A large number of shank flanges 31 (only one of which is shown)are rigidly secured to the hammer shank rail 23 by respective screws 38,and each hammer 30 is pivotally supported by a corresponding one of theshank flanges 31. The hammer 30 is comprised of a hammer shank 32 havinga front end part thereof pivotally mounted to the corresponding shankflange 31, and a hammer head 33 mounted to a rear end of the hammershank 32. A cylindrical shank roller 37 is attached to the lower surfaceof the hammer shank 32 at a predetermined location close to the frontend of the same. Further, a back check 10 is erected on the rear endpart of the key 2 in a manner opposed to the hammer 30 from the rearside.

The wippen 3 has a bifurcated lever-mounting part 3 a extending upward,and a piece of bushing cloth (not shown) is bonded to each of holes (notshown) formed in the respective bifurcated portions of thelever-mounting part 3 a. Between the two pieces of bushing cloth, thereis horizontally mounted a pin 3 b. The repetition lever 4 is pivotallymounted to the wippen 3 via the pin 3 b inserted through the mountinghole 44, such that the wippen-mounting part 41 is engaged with thelever-mounting part 3 a. A lever screw 27 is vertically screwed throughthe screw hole 51 formed in the rear end part of the repetition lever 4,such that the lever screw 27 can be screwed in and out, and the leverbutton 28 is formed integrally with the lower end of the lever screw 27.The repetition lever 4 is urged in a returning direction(counterclockwise direction as viewed in FIG. 2) by the repetitionspring 6 mounted to the wippen 3 and engaged in the groove 52. With thisarrangement, when the key 2 is in a released state, the repetition lever4 is held in a state pivotally moved to a return side by the resilientforce of the repetition spring 6, and the lever button 28 is held incontact with the upper surface of the wippen 3. The angle of therepetition lever 4 in the key-released state can be adjusted by turningthe lever screw 27.

In the vicinity of the jack guide hole 45 of the repetition lever 4, thehammer 30 is disposed on the upper surface of the repetition lever 4 viathe shank roller 37. As shown in FIG. 5, the shank roller 37 is formedto have a width approximately equal to the distance between the outerends of the respective wall parts 45 a and 45 a defining the jack guidehole 45, so that the shank roller 37 can be placed on the wall parts 45a and 45 a in a manner extending over the entire width of the jack guidehole 45. To the upper surface of the skin-mounting part 46 is affixedthe lever skin 39 in a manner opposed to a drop screw 7 screwed into theshank flange 31 from below such that it can be screwed in and out. Withthis arrangement, it is possible to turn the drop screw 7 for adjustmentof the amount of downward projection thereof, to thereby adjust timingin which the repetition lever 4 comes into abutment with the drop screw7 via the lever skin 39.

The jack 5 is formed into an L-shape by a hammer push-up part 5 avertically extending and having a rectangular shape in cross section,and a regulating button abutment part 5 b extending rearward from alower end of the hammer push-up part 5 a substantially at right anglesthereto. The jack 5 has its corner pivotally attached to the front endof the wippen 3. An upper end of the hammer push-up part 5 a is engagedin the jack guide hole 45 of the repetition lever 4 such that the upperend of the hammer push-up part 5 a can move in the front-rear direction.In the key-released state, the upper end of the hammer push-up part 5 ais opposed to the shank roller 37 with a slight space therebetween.Further, the jack 5 is urged in a returning direction (counterclockwisedirection as viewed in FIG. 2) by the repetition spring 6 urging therepetition lever 4.

A jack button screw 9 for adjusting an angular position of the jack 5 isscrewed through an intermediate portion of the hammer push-up part 5 aof the jack 5 in the front-rear direction such that it can be screwed inand out. A jack button 12 is formed integrally with an end of the jackbutton screw 9. In the key-released state, the jack button 12 is inabutment with a spoon 13 erected on the wippen 3. Therefore, by turningthe jack button screw 9, it is possible to adjust the angular positionof the jack 5 in the key-released state.

This angle adjustment by the jack 5 is performed with reference to themarking lines 57 a or the lower stepped parts 56 formed in therepetition lever 4 as shown in FIG. 4. More specifically, in the casewhere the marking lines 57 a are used as the reference, the point ofintersection between the rear-side marking line 57 a and the uppersurface of the repetition lever 4 is set to a reference point B, and thejack button screw 9 is turned so as to align a rear surface 5 c of thejack 5 with the reference point B, whereby the jack 5 is adjusted to apredetermined angular position. In this state, the rear surface 5 c ofthe jack 5 is aligned with the front surface of the lower stepped part56 based on the angular relationship between the marking line 57 a andthe front surface of the lower stepped part 56. Therefore, by using thelower stepped parts 56 as the reference and aligning the rear surface 5c of the jack 5 with the front surface of the lower stepped parts 56, itis also possible to adjust the jack 5 to a predetermined angularposition. As described above, the angular position of the jack 5 can beadjusted using either of the marking lines 57 a and the lower steppedparts 56.

On the other hand, a regulating rail 40 is screwed onto the lowersurface of the hammer shank rail 23. A regulating button 8 forrestricting upward pivotal motion of the jack 5 is screwed into thelower surface of the regulating rail 40 such that it can be screwed inand out, and is opposed to the leading end of the regulating buttonabutment part 5 b of the jack 5, with a predetermined spacetherebetween.

The operation of the action 1 configured as above is basically the sameas that of the conventional action described hereinbefore. Morespecifically, as the key 2 is depressed in the key-released stateillustrated in FIG. 2, the wippen 3 is pushed up via the capstan button25 to pivotally move upward, and the repetition lever 4 and jack 5mounted to the wippen 3 also pivotally move upward along with the wippen3. Along with this pivotal motion, the repetition lever 4 comes intoabutment with the drop screw 7 via the lever skin 39, and at the sametime the jack 5 pushes up the hammer 30 via the shank roller 37 topivotally move the hammer 30 upward. Thereafter, when the hammer 30pivotally moves immediately close to a position for striking a string Sstretched above, the jack 5 comes into engagement with the regulatingbutton 8 whereby the jack 5 is released from the shank roller 37. Thisdisconnects the hammer 30 from the action 1 and the key 2 to strike thestring S in a free rotation state.

After having struck the string S, the hammer 30 pivotally returns in theopposite direction to be stopped by the back check 10. Then, when thekey 2 is released, the hammer 30 is released from the back check 10 atwhich it is stopped, and in timing in which the key 2 is returned to apredetermined height, the repetition lever 4 moves away from the dropscrew 7 and is pivotally moved about the wippen 3 by the resilient forceof the repetition spring 6 to return in the counterclockwise direction,to thereby push up the hammer 30 via the shank roller 37. Thus, the jack5 is pivotally returned by the resilient force of the repetition spring6 to be positioned under the shank roller 37, whereby a followingstring-striking operation can be reliably performed even when the key 2is not completely returned, thereby ensuring the capability of repeatedkey striking.

As described above, according to the present embodiment, since therepetition lever 4 is formed by an ABS resin molded article which ismolded by a long fiber process, and contains relatively long carbonfibers having a length of 0.5 to 2 mm as reinforcing long fibers, it ispossible to obtain a very high rigidity, i.e. a rigidity not lower thanthat of a wooden repetition lever. As a result, deflection of therepetition lever 4 occurring in pushing up the hammer 30 after havingstruck the string can be suppressed, which enables the repetition lever4 to perform the operation of pushing up the hammer 30 in predeterminedtiming. Further, since the ABS resin molded article molded by the longfiber process is as excellent in shape retainability and dimensionalstability as a molded article of a single synthetic resin, it ispossible to reduce deformation, such as warpage and torsion, of therepetition lever 4, and expansion and contraction of the same due todryness and wetness, to much smaller amounts than in the case where therepetition lever 4 is made of wood. Thus, the stable operation of therepetition lever 4 can be ensured, and the capability of repeated keystriking can be enhanced.

Further, in the present embodiment, since carbon fibers are used as thereinforcing long fibers contained in the repetition lever 4, it ispossible to increase the electric conductivity of the repetition lever 4to thereby reliably release static electricity generated by frictionbetween the repetition lever 4 and other component parts including thehammer 30, to thereby prevent the repetition lever 4 from beingelectrostatically charged. This makes it possible to suppress attachmentof dust to the repetition lever 4 and its neighborhood, therebymaintaining excellent operation and appearance of the repetition lever4.

Further, in the present embodiment, since the ABS resin having arelatively high adhesiveness is used as the thermoplastic resin forforming the repetition lever 4, the lever skin 39, the pieces of bushingcloth, and other component parts can be easily mounted to the repetitionlever 4 by bonding, which increases the ease of assembly of therepetition lever 4.

FIG. 3 shows results of a test carried out so as to confirm effects ofreinforcement of rigidity of the repetition lever according to thepresent embodiment, together with those of a test on ComparativeExample. The repetition lever of Comparative Example is made of wood(hornbeam), and the present embodiment and Comparative Example areidentical in size and shape. In the test, in a state where the oppositeends of each repetition lever are held, displacement of the repetitionlever was measured while applying load from above to a central portionthereof, and rigidity of the repetition lever was calculated based onthe relationship between the load and the displacement measured at thetime. Further, the same number of samples of each of the embodiment andComparative Example were prepared. FIG. 3 shows the relationshipsbetween the respective average loads and average displacements of theembodiment and Comparative Example.

As shown in FIG. 3, according to the test result, it was confirmed thatthe rigidity of the repetition lever according to the present embodimentwas increased by approximately 13% in comparison with that ofComparative Example, and the repetition lever of the present embodimenthas a considerably larger rigidity than the wooden repetition lever.Further, although not shown, it was also confirmed that variation inrigidity among the samples is smaller in the present embodiment. Asdescribed above, insofar as the repetition levers have the same size andshape, it is possible to obtain a considerably larger rigidity when thematerial of the present embodiment is used than when the repetitionlever is made of wood. Therefore, by forming the aforementioned first tothird recessed parts 49, 50, and 54 (reduced cross-sectional areaportions) in the repetition lever 4, it is possible to reduce the weightof the repetition lever 4 as much as possible while maintaining the samerigidity as that of the conventional wooden repetition lever having nosuch reduced cross-sectional area portions, thereby enhancing thecapability of repeated key striking.

Further, since the wall parts 45 a of the jack guide hole 45 of therepetition lever 4 are chamfered, and the shank roller 37 of the hammer30 is disposed on the wall parts 45 a, the contact area between therepetition lever 4 and the shank roller 37 is reduced, which makes itpossible to reduce frictional resistance to thereby reduce the staticload on the key. Although not shown, it was confirmed from a testtherefore that the static load on the key is reduced by 1 to 3 g.

It should be noted that the present invention is by no means limited tothe embodiment described above, but it can be practiced in variousforms. For example, although in the embodiment, the ABS resin is used asa thermoplastic resin, and the carbon fibers are used as reinforcinglong fibers, it is possible to use other appropriate materials. Forexample, glass fibers may be employed for the latter. Further, althoughin the embodiment, the first to third recessed parts 49, 50, and 54 areformed as reduced cross-sectional area portions for reducing the weightof the repetition lever, if priority is given to rigidity, such reducedcross-sectional area portions may be dispensed with. Furthermore,although in the embodiment, the present invention is applied to therepetition lever for an acoustic grand piano, it may be applied to arepetition lever for a grand-type electronic piano and one for anautomatic playing piano. It is to be further understood that variouschanges and modifications may be made without departing from the spiritand scope thereof.

INDUSTRIAL APPLICABILITY

As described above, the present invention enables a repetition lever forproviding the capability of repeated key striking of a grand piano tostably perform required operations, and hence it is useful in improvingthe capability of repeated key striking.

1. A repetition lever for a grand piano, which performs the operation ofpushing up a hammer after the hammer has struck a string, wherein therepetition lever is formed by a molded article of a thermoplastic resincontaining long fibers for reinforcement, the molded article beingmolded by a long fiber process, wherein the repetition lever has a shankroller-pushing part having left and right wall parts which define a jackguide hole for guiding a jack and on which a shank roller of the hammerrides, and wherein each of the left and right wall parts has left andright upper edges chamfered.
 2. A repetition lever as claimed in claim1, wherein the long fibers have a length not shorter than 0.5 mm.
 3. Arepetition lever as claimed in claim 1, wherein the long fibers arecarbon fibers.
 4. A repetition lever as claimed in claim 1, wherein thethermoplastic resin is an ABS resin.
 5. A repetition lever as claimed inclaim 1, wherein the repetition lever has a reduced cross-sectional areaportion for reducing weight thereof.
 6. A repetition lever as claimed inclaim 1, wherein the shank roller-pushing part has at an outer sidesurface thereof a marking line as a reference in adjusting an angularposition of the jack.
 7. A repetition lever for a grand piano, whichperforms the operation of pushing up a hammer after the hammer hasstruck a string, wherein the repetition lever is formed by a moldedarticle of a thermoplastic resin containing long fibers forreinforcement, the molded article being molded by a long fiber process,wherein the repetition lever has a shank roller-pushing part having leftand right wall parts which define a jack guide hole for guiding a jackand on which a shank roller of the hammer rides, and wherein the shankroller-pushing part has at a left and/or a right outer side surfacethereof a marking line as a reference in adjusting an angular positionof the jack.
 8. A repetition lever as claimed in claim 7, wherein thelong fibers have a length not shorter than 0.5 mm.
 9. A repetition leveras claimed in claim 7, wherein the long fibers are carbon fibers.
 10. Arepetition lever as claimed in claim 7, wherein the thermoplastic resinis an ABS resin.
 11. A repetition lever as claimed in claim 7, whereinthe repetition lever has a reduced cross-sectional area portion forreducing weight thereof.